Explain the factors affecting bond length.

Hint :This is a very interesting question. To answer this question you should have the knowledge of the factors that can affect bond length. There are many factors which can affect the bond length in different manners. Some of them have been mentioned and also discussed in brief in the below section.

Complete Step By Step Answer:
First factor affecting bond length is that when the size of the atoms increases, the bond length also increases. For example, the order of the bond length of H-X is$HF < HCl < HBr < HI$. It is because the size of fluorine atoms is smallest among all the halogens and the size of the iodine is the largest. Second factor affecting the bond length is that when the multiplicity of the bond increases, the bond length decreases. It means that the bond length of the triple bond is smaller than the bond length of double bond and it is smaller than the bond length of the single bond. Third factor is based upon s-character. It means that greater the s-character, smaller will be the hybrid orbital and hence shorter will be the bond length. For example, $s{p_3} > s{p_2} > sp$.

Note :
If we talk about polar bond length, it is usually smaller than the theoretical non-polar bond length. Bond length also gets affected by the oxidation number of the central atom like when the positive charge on the atom is higher, then the bond length is smaller. If you want to find the length of the bond, then it is determined by the bonded electrons.